垂直直立石墨烯纳米墙的制备及光热感应

基于等离子体增强化学气相沉积(PECVD)技术,通过调节实验参数,在绝缘衬底玻璃上成功制备出了三维垂直直立的石墨烯纳米墙(GNWs)材料.生长过程中发现石墨烯的质量和尺寸大小与相应的生长时间有关,利用拉曼(Raman)光谱、扫描电子显微镜(SEM)、原子力显微镜(AFM)等仪器对石墨烯纳米墙作了表征.并且,利用石墨烯纳米墙超高的比表面积和优异的散热特性,发现垂直直立的石墨烯纳米片-玻璃杂化混合材料在光热感应上有着良好的响应,将有望促进垂直直立石墨烯纳米片-玻璃杂化的混合材料在透明的太阳热装置和绿色保暖建筑材料上的应用.     

不同排烟方式HAT循环性能对比

对三种不同排烟方式HAT循环的模拟分析表明,在总压比一定时,排烟方式对比功影响很小,采用引风机排烟的HAT循环比直接排烟及回热法排娴的电效率最多分别高出1和1.5个百分点,最高效率时的引风机压比在1.5～1.6左右.引风机排烟带来的压缩耗功下降和湿化器出水温度降低是效率升高的主要原因.水回收率相对偏低,且性能受烟气冷凝温度和引风机压比影响较大.     

β-delayed neutron decay of 21N

The β-delayed neutron and γ spectra of neutron-rich nucleus ²¹N using β-γ and β-n coincidence measurements were presented in this paper. Thirteen new neutron groups ranging from 0.28 MeV to 4.98 MeV and with a total branching ratio 88.7±4.2% were observed. One γ transition among the excited states of ²¹O, and four γ transitions among the excited states of ²⁰O were identified in the β decay chain of ²¹N. The ungated half-life of 83.8±2.1 ms was also determined for ²¹N.     

超高效液相色谱-串联质谱法同时测定牛肉中18种食源性兴奋剂类药物残留

建立了超高效液相色谱-串联质谱（UHPLC-MS/MS）检测牛肉中18种食源性兴奋剂类药物残留的方法。牛肉组织经酸化乙腈提取,Captiva小柱脱脂净化后,用无水硫酸镁干燥,上清液氮吹浓缩,残渣用甲醇-水（7：3,v/v）溶解。采用Agilent Zorbax Phenyl-Hexyl色谱柱分离,以5 mmol/L醋酸铵水溶液（含0.01%（v/v）醋酸）和甲醇-乙腈（7：3,v/v）作为流动相进行梯度洗脱,在电喷雾正负离子切换模式下以多反应监测（MRM）方式检测,用基质匹配标准曲线外标法定量。结果表明,18种食源性兴奋剂类药物在0.10~50 μg/L范围内线性关系良好,相关系数（R²）≥ 0.9950;在0.4、1.0和2.0 μg/kg添加水平下的回收率为57.3%~117.5%,相对标准偏差为3.1~15.6%（n=5）;方法的检出限和定量限分别为0.0006~0.0900 μg/kg和0.0020~0.3000 μg/kg。该法可以实现对牛肉样本中18种兴奋剂类药物残留的定性定量分析,具有简单、快速、准确性高的特点。     

SHPB混凝土实验中试件尺寸的影响（英文）

分离式霍普金森压杆(SHPB)实验常被用来获得混凝土类材料的动态压缩强度,所得数据对建立本构方程有重要作用,因此需要对其进行正确解释或分析。利用最新的混凝土材料模型研究了SHPB实验中试件尺寸的影响。藉由混凝土试件的体积考虑动态尺寸效应的影响,并提出了一个计算由于惯性(约束)效应引起的动态增强因子的新经验公式。结果表明:新经验公式与不同尺寸混凝土的SHPB模拟结果吻合得很好,且惯性(约束)效应引起的动态增强因子随着试件尺寸的增大而增大。     

Off-stoichiometry indexation of BiFeO_3 thin film on silicon by Rutherford backscattering spectrometry

BiFeO_3 is a multiferroic material with physical properties very sensitive to its stoichiometry.BiFeO_3 thin films on silicon substrate are prepared by the sol–gel method combined with layer-by-layer annealing and final annealing schemes.X-ray diffraction and scanning electron microscopy are employed to probe the phase structures and surface morphologies.Using Rutherford backscattering spectrometry to quantify the nonstoichiometries of BiFeO_3 thin films annealed at 100?C–650?C.The results indicate that Bi and Fe cations are close to the stoichiometry of BiFeO_3,whereas the deficiency of O anions possibly plays a key role in contributing to the leakage current of 10~(-5) A/cm~2 in a wide range of applied voltage rather than the ferroelectric polarizations of BiFeO_3 thin films annealed at high temperature.     

A rapid and convenient experimental method of absolutely calibrating transmission of x-ray flat-response filter

We develop a rapid and convenient experimental method of absolutely calibrating the transmission of an x-ray flatresponse filter. The calibration experiment is performed on a small laser-target facility, and a set of high resolution holographic flat-field grating spectrometers is used as a discrimination system of the laser-produced x-ray source. Given that the holographic flat-field grating has a relatively large width, the grating is divided into two regions for use in that direction,where one region has the filter added and the other region does not. The filter transmission is determined by dividing the x-ray signal counts detected when the filter is in the line of sight by those detected when the filter is out of the line of sight.We find that the calibration results of this experiment agree with the calibration results using a synchrotron radiation source,as well as simulation results. Our method is not only highly reliable but also rapid and convenient.     

嗓音多频带非线性分析的声带病变识别

提出了一种嗓音多频带非线性分析的声带病变识别方法,以提高声带病变嗓音的识别率。首先采用Gammatone听觉滤波器组对嗓音信号进行滤波,求取每个频带下的最大李雅普诺夫指数;对映射到核空间的数据采用高斯最大似然度准则优化核函数,然后采用优化核主成分分析算法实现特征抽取。识别实验表明,多频带最大李雅普诺夫指数的识别率比传统的MFCC和最大李雅普诺夫指数分别有6.52%和8.45%的提高,且采用优化核主成分分析算法比传统核主成分分析算法有更好的抽取效果.将多频带非线性分析和优化核主成分分析算法结合,识别率提升至97.82%。      

鄂尔多斯盆地奥陶纪中央古隆起水平迁移规律——来自于同沉积记录的证据

鄂尔多斯盆地奥陶纪中央古隆起是盆地内的重要油气聚集区,其成因一直是大家关注的热点.利用丰富的钻井资料对古隆起中东部地区中奥陶统马五段地层的沉积特征进行详细的分析,编制出了马五段各层段的厚度等值线图,圈出了各时期的沉降中心位置,发现在马五₈~马五₅时期,沉降中心基本以向南迁移为主,伴随着一定程度的向西迁移;在马五₄³到马五₄¹时期,沉降中心以向西的迁移为主,伴随微弱的向南迁移.这种迁移过程支持鄂尔多斯盆地西、南缘在奥陶纪时发育双前陆盆地,“L”型中央古隆起是在早-中奥陶世时受该双前陆盆地前缘隆起相互叠加的影响.     

不同温度下HMX和RDX晶体的感度判别和力学性能预估分子动力学比较研究

为探讨和比较炸药黑索金(RDX)和奥克托今(HMX)晶体的结构、 能量和力学性质随温度的递变规律, 在COMPASS力场和NPT系综下, 对其合适的等原子数超晶胞模型分别进行5个温度(195, 245, 295, 345和395 K)下的分子动力学(MD)周期性模拟研究. 结果表明, 随着温度的升高, RDX和HMX晶体引发键N-NO₂的最大键长(L_max)的逐渐增大以及引发键连双原子作用能(E_N-N)和内聚能密度(CED)的逐渐减小均与感度随温度升高而增大的实验结果一致; 且在各温度下, RDX晶体的L_max均大于HMX晶体的L_max, 与HMX相比, RDX的E_N-N和CED均较小, 上述结果与RDX比HMX感度大的实验结果相符. 由此表明, 在一定条件下, L_max, E_N-N和CED可用于高能物质的热和撞击感度的相对大小的判别. 基于MD模拟原子运动轨迹, 用静态法求得2种晶体的弹性力学性能, 发现拉伸、 体积和剪切模量均随温度的升高而递减, 与实验结果一致.